A motion guide device equipped with rolling elements, such as balls or rollers, is used to be arranged in guiding parts of a moving object moving linearly. While being used, the device has a guide function with the help of rolling movements of the rolling elements. For using this motion guide device, good lubricity should be given to the rolling elements and rolling-element rolling surfaces on which the rolling elements roll. If the device is used with no lubricity, wear of the rolling parts may increase or early flaking may be caused.
The applicant is proposing a lubricating technique (for example, refer to patent reference 1) which uses lubricating devices “QZ (trademark of THK Co., Ltd.)” attached to both ends of a moving member of a motion guide device, in which the lubricating devices are able to supply a small amount of lubricant to only rolling surfaces on which the rolling elements roll. Inside of each of the lubricating devices, there are provided a high oil-retaining storage for storing lubricant, a high-density storage for applying the lubricant to the rolling surfaces, and oil-amount adjusting plates for adjusting an amount of flow of lubricant being supplied from the high oil-retaining storage to the high-density storage. How to supply the lubricant is based, in principle, on the capillary action on which devices such as felt pens are produced. Use of this lubricating method enables a small amount of lubricant to be applied onto the rolling-element rolling surfaces, whereby the lubricating capability is held over a long period of time.    Patent reference 1: Japanese Patent Laid-open Publication No. 2004-3545